Vehicle control systems that do not require a mechanical linkage between the operator controlled pedals and the components which are controlled by the pedals are known in the art, and are sometimes referred to as drive-by-wire control systems. The engine control system is one system which can include a drive-by-wire engine controller to obviate the need for a mechanical linkage between the accelerator pedal and the engine. One type of drive-by-wire engine controller known in the art includes a pedal position sensor which senses the angular position of the pedal lever which pivotably supports the accelerator pedal. The pedal position sensor produces an electric signal proportional to the angular position of the pedal lever. This signal is then sent to an electronic control module (ECM) which regulates the output of the engine.
Some of the pedal position sensors known in the art utilize potentiometers to sense the angular position of the pedal lever. The potentiometer typically has one member connected to the pedal lever and another member connected to a surface which is stationary with respect to the vehicle, such as the bulkhead. Several problems are associated with this type of sensor. Potentiometers generally have at least one pair of surfaces in direct sliding contact. This can cause wear between the surfaces in contact and degradation in performance of the sensor. Moreover, friction is produced between the surfaces in contact and, depending on its magnitude, can require additional effort by the vehicle operator to depress the pedal or a spring to counteract the friction force. Periodic adjustment of the pedal lever can be required if the friction force is sufficiently large and variable.
The potentiometer must be shielded from the dirt and chemicals which can be on the operator's shoes and from inadvertent jolts to the potentiometer by the operator. Shielding such a potentiometer can be difficult since flexible shielding must be used due to the variations in size of the potentiometer associated with movement of the pedal lever.
It is also known to provide the drive-by-wire controller with a pedal force sensor which is able to sense whether the angular displacement of the pedal lever is caused by the application of an external force to the lever, such as the operator stepping on the pedal. The pedal force sensor is connected to the ECM and produces an electrical signal to indicate whether a force is sensed by the sensor. The ECM is programmed to sense this signal and cause the engine to idle if there is no force sensed. This reduces the possibility of unintended movement of the vehicle by a reason other than the operator stepping on the accelerator pedal.
Several problems are associated with drive-by-wire controllers having pedal position sensors and pedal force sensors. The pedal position and force sensors are sometimes attached to different parts of the pedal lever and vehicle increasing the effort and expense necessary to manufacture and install the lever. A further problem associated with separate attachments of the sensors is that each sensor must be separately shielded. The separate locations of the pedal position and force sensors on the pedal lever also contribute to increased vehicle assembly effort and expense since a separate set of wires for each sensor must be routed from the respective sensor locations through the passenger and engine compartments to the ECM.